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fetching data from the database
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Join Date: Jun 2007
Posts: 15
Reputation: 
Solved Threads: 0
Newbie Poster
Hi,
I have written a jsp file to fetch data from a database table and display it in the form of a table in jsp. The idea is to generate a dynamic table. I have written the following code.
#
<%@page import="java.sql.*"%>
<html>
<head>
<title>The alert table</title>
</head>
<body>
<h1>Alerts</h1>
<%
Connection conn = null;
ResultSet rs1 = null;
Statement stmt = null;
ResultSetMetaData rsmd = null;
String query="select * from alertdata";
try {
Class c = Class.forName("org.postgresql.driver");
conn = DriverManager.getConnection("jdbc:postgresql://192.168.128.150:5432/thirdeye", "postgres", "postgres");
stmt = conn.createStatement();
rs1 = stmt.executeQuery(query);
int columns=0;
rsmd = rs1.getMetaData();
columns = rsmd.getColumnCount();
}
catch (SQLException e) {
System.out.println("Error occurred " + e);
}
%>
<table width="90%" border="1">
<tr>
<% // for the header cells
try {
for (int i=1; i<=columns; i++) {
out.write("<th>" + rsmd.getColumnLabel(i) + "</th>");
}
%>
</tr>
<% // for each row in the database table
while (rs1.next()) {
out.write("<tr>");
for (int i=1; i<=columns; i++) {
out.write("<td>" + rs1.getString(i) + "</td>");
}
out.write("</tr>");
}
// close the connection and the statement
stmt.close();
conn.close();
}
catch (SQLException e) {
System.out.println("Error " + e);
}
finally {
try {
if (stmt != null)
stmt.close();
} catch (SQLException e) {}
try {
if (conn != null)
conn.close();
} catch (SQLException e) {}
}
%>
</table>
</body>
</html>
#
However this gives me an error, cannot resolve columns.
Please help.
Saswati
I have written a jsp file to fetch data from a database table and display it in the form of a table in jsp. The idea is to generate a dynamic table. I have written the following code.
#
<%@page import="java.sql.*"%>
<html>
<head>
<title>The alert table</title>
</head>
<body>
<h1>Alerts</h1>
<%
Connection conn = null;
ResultSet rs1 = null;
Statement stmt = null;
ResultSetMetaData rsmd = null;
String query="select * from alertdata";
try {
Class c = Class.forName("org.postgresql.driver");
conn = DriverManager.getConnection("jdbc:postgresql://192.168.128.150:5432/thirdeye", "postgres", "postgres");
stmt = conn.createStatement();
rs1 = stmt.executeQuery(query);
int columns=0;
rsmd = rs1.getMetaData();
columns = rsmd.getColumnCount();
}
catch (SQLException e) {
System.out.println("Error occurred " + e);
}
%>
<table width="90%" border="1">
<tr>
<% // for the header cells
try {
for (int i=1; i<=columns; i++) {
out.write("<th>" + rsmd.getColumnLabel(i) + "</th>");
}
%>
</tr>
<% // for each row in the database table
while (rs1.next()) {
out.write("<tr>");
for (int i=1; i<=columns; i++) {
out.write("<td>" + rs1.getString(i) + "</td>");
}
out.write("</tr>");
}
// close the connection and the statement
stmt.close();
conn.close();
}
catch (SQLException e) {
System.out.println("Error " + e);
}
finally {
try {
if (stmt != null)
stmt.close();
} catch (SQLException e) {}
try {
if (conn != null)
conn.close();
} catch (SQLException e) {}
}
%>
</table>
</body>
</html>
#
However this gives me an error, cannot resolve columns.
Please help.
Saswati
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•
Join Date: May 2007
Posts: 4,433
Reputation: 
Solved Threads: 507
You have defined 'columns' locally inside a try-catch block and are attempting to use it in another block. Move the declaration outside the first block so that it is visible to the second.
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•
Join Date: Jun 2007
Posts: 15
Reputation:
Solved Threads: 0
Newbie Poster
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Originally Posted by Ezzaral 
You have defined 'columns' locally inside a try-catch block and are attempting to use it in another block. Move the declaration outside the first block so that it is visible to the second.
Saswati
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Join Date: Dec 2004
Posts: 4,181
Reputation:
Solved Threads: 481
You aware that accessing any database with JSP is not recommended and should be avoid. Servlets been design for this task...
Learn to see in another's calamity the ills which you should avoid.
Publilius Syrus
(~100 BC)
LJC - London Java Community, Graduate & Undergraduate Software Development Community, JAVAWUG (Java Web User Group), The London Android Group
Publilius Syrus
(~100 BC)
LJC - London Java Community, Graduate & Undergraduate Software Development Community, JAVAWUG (Java Web User Group), The London Android Group
•
•
Join Date: Jun 2007
Posts: 15
Reputation:
Solved Threads: 0
Newbie Poster
Hi,
I am very new in java/jsp. Could you please explain me how to use servlets instead of jsp.
Thanks a lot in advance.
Saswati
I am very new in java/jsp. Could you please explain me how to use servlets instead of jsp.
Thanks a lot in advance.
Saswati
•
•
Join Date: Dec 2004
Posts: 4,181
Reputation:
Solved Threads: 481
Story of a Servlet
Basic Servlet Structure also there is more ont that site
Introduction to Servlets
And there many-many more you just need to specify what exactly you are looking for
Basic Servlet Structure also there is more ont that site
Introduction to Servlets
And there many-many more you just need to specify what exactly you are looking for
Learn to see in another's calamity the ills which you should avoid.
Publilius Syrus
(~100 BC)
LJC - London Java Community, Graduate & Undergraduate Software Development Community, JAVAWUG (Java Web User Group), The London Android Group
Publilius Syrus
(~100 BC)
LJC - London Java Community, Graduate & Undergraduate Software Development Community, JAVAWUG (Java Web User Group), The London Android Group
•
•
Join Date: Jun 2006
Posts: 7,600
Reputation:
Solved Threads: 462
Also you should consider using JSTL instead of embedding business logic / scriptlets inside your JSP file.
Read the following:
http://java.sun.com/products/jsp/jstl/
http://www.developer.com/java/ejb/article.php/1447551
Read the following:
http://java.sun.com/products/jsp/jstl/
http://www.developer.com/java/ejb/article.php/1447551
Last edited by ~s.o.s~; Jun 28th, 2007 at 12:34 pm.
I don't accept change; I don't deserve to live.
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